1. Field of the Invention:
This invention relates to a lens drive device for auto-focusing, manual power focusing, or power zooming of a camera.
2. Description of the Related Art:
It has already been known to provide a lens drive device having the auto-focus and manual focus made selectively operable. In this conventional device, the auto-focus mode and the manual focus mode, being modes utterly independent of each other, could be selectively set by the photographer. With the device previously set in the manual focus mode, therefore, when the photographer was to perform focusing automatically, he had to manipulate a mode selector so that the device was switched from the manual to the automatic focusing mode. After shootings had been made with manual focusing, if the switching back to the auto-focus mode was forgot to do, the photographer, when in the next shot under the mistaken presumption that the auto-focus mode was operating, would fail, despite actuation of a camera release, to execute the automatic focusing, and, after having become aware of the mode being left unchanged from the manual, would then have to turn back the mode to the automatic one before the release button was pushed down again. This implies that there was a high possibility of missing good shutter chances.
Also, the necessity of choosing the manual focus mode is limited to particular photographic situations where the automatic focusing gives undesired results, for example, a focusing is desired independently of the position of a subject of principal interest. Therefore, there has been no need of making independently settable the auto-focus and manual focus modes. But, because a manually operating member was necessarily used for changing over between the auto-focus and manual focus modes, the above-described problems arose.
Also, in case when, in addition to the auto-focus function, the power zoom function, which is performed with a motor by pushing down an operating button, is installed in the camera, another problem arose that while zooming was being performed by pushing down the operating button, the release button was pushed down to operate the auto-focus function, with the result that the zooming operation and the focusing operation occurred simultaneously which made it difficult to quickly establish the in-focus condition.
As the capabilities of the camera are broadened to include the auto-focusing, the manual focusing, a motorized visual focusing and the motorized zooming, there will be at least three operating members, giving rise to a problem that the space large enough to admit of the arrangement of these three operating members is not available. Moreover, this will become a cause for mistaken operations.